Glassdoor, founded in 2007 in San Francisco, has grown from nothing to become the second biggest jobs website in North America and one of the fastest-growing job listing websites in the world.

The company, known for its anonymous reviews of companies by staff, employs over 700 people and runs 15 localised sites around the world.

Founder and CEO Robert Hohman has led Glassdoor on the journey from startup, to scale-up, to established player. So what advice can Hohman share with would-be entrepreneurs?

"I think it's really important to focus," Hohman told Business Insider. "When I am asked by entrepreneurs for my advice, that's probably the thing I keep coming back to again and again and again: focus, focus, focus."

"I think people underestimate the de-focusing and the inherent cost that come with opening a very, very wide front of activities you're working on," Hohman said.

Hohman has a specific warning for digital businesses considering international expansion. He told BI: "Being a web or internet company means it's a heck of a lot easier to expand internationally than if you were running a factory — you'd have to build the machines, install them and all that. It's an inherently easier thing to do. It's very tempting to do it quickly.

"Get your core machine working in one location, one country, understand it deeply, and only then begin to think about going global."

He added: "It's hard to scale period. As you grow and you begin to execute in other countries it's really important to understand and to build a local presence. It's a challenge. Many companies are doing it faster than they've ever done before and that is inherently complicated."